Lubricating oil



Patented Aug. ll, ieez @NETE STATES PATENT OFFICE LUBRICATING OIL ware No Drawing. Original application February 23, 1938, Serial No. 191,955. Divided and this application July 18, 1940, Serial No. 346,181

2 Claims.

Our invention relates to lubricating oils and more particularly to a lubricating oil of high quality containing an addition agent improving its film strength and oiliness.

This application is a division of application, Serial No. 191,955, filed February 23, 1938, Patent No. 2,213,804 issued September 3, 1940, which application is a continuation in part of application Serial No. 65,090, filed February 21, 1936.

Present-day mechanical devices require lubricating oils of high film strength and of high oiliness characteristics. It has been found that the present-day hydrocarbon lubricants of the Very highest quality are deficient in these two very important characteristics, These two properties are of vital importance under conditions of thin film lubrication where the lubricant has been squeezed from between the friction surfaces due to high pressure, slow speeds, and other causes. It is readily seen that the viscosity or the body of the lubricant plays no part in this type of lubrication and that the remaining filmof oil must have a very high film strength and be of high oiliness value to prevent rupture of the film of the lubricant, which would cause seizure, and tend to keep the coefficient of friction as low as possible.

- Mechanical devices are being designed for higher pressure operation and the film strength of the best quality straight hydrocarbon lubricant has been found to be too low. It will be obvious that an invention which provides the means of improving the film strength of these lubricants is of great importance to the art of lubricant manufacture and to the designer and fabricator of mechanical devices.

Substantially all machines operate in part or at times totally under conditions of boundary or thin film lubrication, under which conditions the oiliness or unctuosity of the lubricant is the first and primary requisite of efficient operation. Those skilled in the art of lubricant manufacture or machine manufacture will readily appreciate the value of an invention that will improve the oiliness Of these otherwise high quality lubricants.

In starting idle mechanical equipment which is lubricated from a sump by pumping or circulating the lubricant, there is always a short period of time in which the rubbing surfaces must operate under conditions of dry friction if ordinary hydrocarbon lubricants are used. With dry friction, the wear on friction surfaces is extreme; and during cold. weather when the lubricant is sluggish or during periods when the lubrieating system is not functioning properly for one reason oranother, rubbing surfaces may not only suffer considerable wear but may be damaged to the point where they must be replaced. The product of our invention has a very important property of reacting with the metal surfaces, penetrating or absorbing on the metal surfaces, and leaving a film of lubricant with high oiliness character, which remains on the metal surface irrespective of the length of time the machine has been idle.

This high oiliness film gives very even and smooth operation, which may be easily discerned by the experienced operator and lubricating engmeer. I

When the hydrocarbon lubricants are diluted with unburned fuel or with other light hydrocarbons the small degree of oiliness of the original hydrocarbon lubricant is greatly decreased. We have found that the addition of the products of our invention to hydrocarbon lubricants more than compensates for the loss in oiliness and load-carrying ability from dilution,

Most oils and greases change color and/or deteriorate when exposed to light or the oxygen of the air during use or storage. Deterioration during use of a hydrocarbon oil in an internal combustion engine takes the course of sludge formation and the production of soluble acids and/0r corrosive materials; Furthermore, ordinary lubricants are low in film strength.

In the prior art, it has been suggested that oxidation inhibitors or antioxidant materials such as weakly basic nitrogen compounds including the aliphatic amines and the like, or metallic compounds including compounds of tin, chromium, zinc and the like, be employed.

One object of our invention is to provide a lubricant which has a reduced tendency to oxidize and form sludge and soluble oxidation products.

Another object of our invention is to provide a lubricant of increased film strength.

A further object of our invention is to provide a stabilized lubricant which produces in use less material corrosive to the parts being lubricated.

A still further object of our invention is to provide a lubricant which may be used from five to ten times as long as ordinary lubricants before it is necessary to discard the lubricant on account of its corrosive action on the parts being lubricated.

Other and further objects of our invention will appear from the following description.

In general, our invention contemplates the adv I I I v v v 1 dition of relatively small; amounts :of: :stable,

' heterocycllc sulphur. compo nds :to hydrocarbon;

= =lubricants. The, hydrocarbon i portion of our i :atoms in a vheterocyclic ring: are: I v i compound may be: comparatively viscous or mom i a viscous; refinedor unrefined, natural or syn- I thetic; In the. parent case; Serial 191,2?55, =we

' claimed organic compounds f containing two zsule 1 e I phur atoms in a heterocyclic ring, broadly. Species claims. directed to 'nonadja'cent: sulphur atoms in a'fieterocyclic ring arealsoclaimed in case.

' efr'y; stable, rm;

fiurthermore none" I I ur nventio n :may bei ma 5 y i i e t t e m nt and, when. added. in an;

erties, improved film strength and long life. In addition, it has been found that these compounds inhibit the formation of finely divided oil-insoluble carbonaceous material commonly known as sludge. This sludge inhibiting property prevents lubricants to which our compounds have been added from darkening in use or storage.

Furthermore, the addition of our compounds to a lubricant increases its load carrying capacity, thus afiording an increased lubricating safety quantities to; i notherwise finished lubricant, j form mixtures having corrosion inhibiting propothe parent'case. In this divisional application I we will claim onlya lubricant havinga hydro- --carbon= oil base and organic compounds contaim ing at least twoadjacent sulphur 'atoms in'a i heterocyclic ;ring, thus keeping: aclear line of z division between theinstant case'andzth parent I I i in practicing our invention; weiuse: only: stable T I =-organic sulphur compounds which may'contain other. inorganic. elements, for example, oxygen;

i hydrogem:phosphorua etc. We are aware of the to; Sommer, i dated Qctober 20, 1 891; sulphuret; i g i g g g g g;ted lard oil andcther oilshaveibeen iused,vbut all I I i I these oils treated: with; sulphur or :sulphur. hloa I i se iw h nthe s a e of i ably we use ;from'.25

z and itslderiuatives such as phenyl thiure ,,,,,2,2o2,45er A s a r r s n d e r. d rive was at r j invention; Prefer c 2 pa cent a: one or mo e z l for these; addition agents t bricating;

same-mag a r'mly' c uncrinai chemical c ma-inane f I f the compounds included in I factor in reducing friction and preventing metal to metal contact in bearing and other rubbing surfaces.

Our invention consists in adding to an otherwise finished lubricant, a suitable amount of a heterocyclic organic compound containing at least one ring consisting of carbon and other atoms but including in such ring at least two sulphur atoms. Other atoms beside carbon and sulphur such as oxygen, nitrogen, and other inorganic elements may be present in the ring with the two or more atoms of sulphur or in other rings or parts of the molecule. Various substituting. groups may be present without impairing the efiectiveness of the two sulphur atom ring. Thus, groups such as alkyl, aryl, arylalkyl, hydroxyl, amino, nitro, carboxyl, cyano, aldehyde, ether, carbinol, and others may be present in any part of the molecule. Selenium and tellurium are to be considered equivalents of sulphur in those cases in which the corresponding compounds exist.

Specific examples of addition agents capable of sionin'the hydrocarbon oil; mom-pa ed byfs'uit QbIefstabiIiZin, ,s i'ongori suspension 7 I I a particular compound or combination of compounds to be used as an addition agent to hydrocarbon oil is to be made considering the use to which the blend is put. Thus, if water is likely to be present during use, a stable sulphur compound or combination of compounds is selected which are not afiected by water; If a particular added stable sulphur compound proves too volatile for its application, a higher boiling stable sulphur compound should be used and the more volatile compound used for blending in a hydrocarbon oil intended for duty at lower temperature. In general, we prefer to use compounds having boiling points over F. Some of these stable sulphur compounds may be too odoriferous for certain purposes. In such cases the odor is covered by asuitable perfuming agent. Such details of practice will be apparent to anyone skilled in the art.

It is sometimes advantageous to combine more than one of these compounds in a blend to obtain particular properties. We accomplish this by mixing two or more of these compounds together and blending the mixture with the hydrocarbon oil or by blending one in the hydrocarbon oil, blending the second into this mixture and so on until the composition is complete.

The various sulphur compounds may give improvement other than film strength to the hydrocarbon oil. For example the sludging tendencies may be decreased by as little as 0.01 per cent of some sulphur compounds. The oxidation characteristics of lubricants is very important in some services, and such is improved by sulphur comoil= ma e used. in. numeral .511 pension or emul "'11.: Trimethylene-LZ-disulfide,' i d' i i aw:

irerm i nt The secede 26f.

pounds as a rule, The ability to reduce friction is another feature contributed to lubricating oils by some sulphur compounds.

To test the effectiveness of these heterocyclic sulphur compounds as corrosion inhibiting agents, we employed a corrosion testing apparatus which comprised an oil container, an electric motor, an electric heater, and a clamp shaft. The oil container comprised an iron cup about four inches in diameter and eight inches deep, equipped with vanes at the sides and bottom thereof. The electric motor was a H. P., operating at 1700 R. P. M. The motor was mounted directly over the oil container. The oil heater was mounted within the oil container and equipped with a temperature control apparatus. The clamping shaft is directly connected to the motor. The other end of the clamping shaft is provided with a bearing in the bottom of the oil container. Adjustable clamps are provided for holding specimen bearings while rotating in the oil container. Test bearings were prepared by sawing automobile half bearing inserts into two one-half width pieces. The test bearings were prepared for test by polishing the bearing surfaces with number 100 emery paper and weighing. Eight hundred cubic centimeters of the oil to be tested were placed in the cup and agitated by rotating the shaft with half of the bearing clamp attached until the oil reached the test temperature of 350 F., being raised to this temperature by the heater. The shaft was then removed and the shaft with test bearings clamped in place and the motor started. Air at a measured rate of 200 cubic centimeters per minute was bubbled through the oil. The motor was stopped at intervals and the test bearings inspected. This process was continued until it was noted that corrosion had commenced. The corroded test bearings were then washed with gasoline and then with a solution containing one part toluene. one part ethyl acetate and one part 96 per cent ethyl alcohol. They were then wiped with a soft cloth, dried in an oven and. weighed. The weight loss of the test bearings was plotted against the time on cross section paper, showing the time elapsing before corrosion began.

A number of bearings were tested by this method, with various lubricating oils by themselves and various lubricating oils with various amounts of thianthrene or other heterocyclic sulphur compounds added. The amount of the addition agent added varied between .05 of one per cent and two per cent. As a result of these tests, it was found that, if a mineral oil without the addition agent could be run for about four hours before corrosion began, a small amount such as 6 of one per cent of thianthrene could be run for about ten hours before corrosion commenced and that, in general, lubricants to which thianthrene had been added were twice as resistant to corrosion and deterioration as the same lubricants to which no addition agent had been added.

This corrosion resisting and inhibiting effect obtained, too, in hydrocarbon oils which were thickened with various soaps to form greases.

It will=be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of our claims. It is further obvious that various changes may be made in details within the scope of our claims without departing from the spirit of our invention. It is, therefore, to be understood that our invention is not to be limited tothe specific details shown and described.

Having thus described our invention, we claim:

1. A lubricant comprising in combination a hydrocarbon oil and a small quantity of trimethylene-1,2-disulphide.

2. A lubricant comprising in combination a hydrocarbon oil and from .05 per cent to 2.0 per cent by weight of trimethylene-lz-disulphide.

BERT H. LINCOLN. GORDON D. BYRKIT. 

